The company I work for recently merged with another company. The two domains (call them ABC.net and XYZ.com) are separate (for the time being) but are connected through a point-to-point T1 and a domain trust is setup and working. My company has an Exchange 5.5 server and the other company has Exchange 2000. If someone in ABC.net wants to send e-mail to someone in XYZ.com, it currently has to traverse the Internet to get there. I have been tasked with the job of getting these two servers to send e-mail destined for each other's domains across the T1, instead of going over the Internet. I have tried setting up the 5.5 server for an SMTP relay using the steps in MS article 259531, but I'm getting a "host unreachable" error in the Internet Mail Service queue. How do we setup the Exchange 2000 server to do the same thing? We can't find anything on MS that really applies to our situation. What am I missing? Thanks!